(a) Field of the Invention
The present invention relates to a display device and in particular, a touch sensible display device.
(b) Description of Related Art
A liquid crystal display (LCD) includes a pair of panels, one of which is provided with pixel electrodes, and the other of which includes a common electrode. A liquid crystal layer with dielectric anisotropy is interposed between the panels. The pixel electrodes are arranged in a matrix and connected to switching elements such as thin film transistors (TFTs), and receive image data voltages row by row. The common electrode covers the entire surface of one of the two panels and is supplied with a common voltage. A pixel electrode and corresponding portions of the common electrode, and corresponding portions of the liquid crystal layer form a liquid crystal capacitor that as well as a switching element connected thereto is a basic element of a pixel.
An LCD generates electric fields by applying voltages to pixel electrodes and a common electrode and varies the strength of the electric fields to adjust the transmittance of light passing through a liquid crystal layer, thereby displaying images.
A touch screen panel is an apparatus which responds to a touch by a finger or a stylus to write characters, to draw pictures, or to instruct a device such as a computer to execute instructions by using icons. The touch screen panel has its own mechanism to determine whether and where a touch exists and it is typically associated with a display device such as an LCD. However, an LCD which includes a touch screen panel is expensive to manufacture due to the cost of the touch screen panel and has low yield rates due to the difficulty of attaching the touch screen panel to the LCD. Also, the combination results in reduction of the luminance of the LCD and an increase in the thickness of the LCD.
It has been developed that sensors including thin film transistors are incorporated into pixels in an LCD instead of a touch screen panel. A sensor senses the variation of light incident on a panel or the variation of pressure exerted on the panel by user's finger or a stylus to inform the LCD of a touch touches on the screen and where the touch occurred.
The sensors and signal lines for the sensors may occupy a significant area in the display panel and thus the aperture ratio of the LCD may be decreased. In addition, the signal lines for the sensors may be disturbed by signal lines for the pixels.